報告書番号

L05015

タイトル（和文）

中間開度における蒸気加減弁の流体振動現象 -蒸気を用いた実験・数値計算による現象解明-

タイトル（英文）

Flow Oscillations on the Steam Control Valve in the Middle Opening Condition- Clarification of the Phenomena by Steam Flow Experiments and Calculations -

概要 （図表や脚注は「報告書全文」に掲載しております）

発電プラント等の蒸気系の流量調節弁は，弁の開度が中間状態の時に配管振動などが発生して配管疲労を起こす可能性があり，プラントの高稼働率化の為にも振動原因の解明と改善策の提案が求められている．当所はこれまでに，空気を用いた実験・CFD計算によって現象の詳細な解明・対策の提案を実施してきた．しかし，プラント内の実流体は蒸気であるため，凝縮や状態量変化などが空気と異なっている．そこで，汎用蒸気設備"WISSH"を用いた実験・蒸気用CFDコード"MATIS-SC"を用いた数値計算を実施し，蒸気加減弁周りの流れ場の詳細を調べた．その結果，これまでに確認された中間開度での圧力変動が発生する事が判明した．

概要 （英文）

A steam control valve might cause vibrations of piping when the valve opening is in a middle condition.For rationalization of maintenance and management of the plant, the valve should be improved, but it is difficult to understand flow characteristics in detailby experiment because flow around the valve is complex 3D structure and becomes supersonic (M>1).Therefore, it is necessary to clarify the cause of the vibrations and to develop improvements by CFD (Computational Fluid Dynamics) technology.In previous researches, we clarified a mechanism of the pressure fluctuations in the middle opening condition and suggested the way to prevent the pressure fluctuations by experiments and CFD calculations. But, as we used air as a working fluid in our previous research instead of steam that is used in the power plant, we couldn’t consider effects of condensation and difference of change of the quantity of state between air and steam.In this report, we have conduct steam flow experimentsby multi-purpose steam experiment apparatus WISSHand CFD calculations by steam flow code MATIS-SC to clarify those effects. As a result, in the middle opening condition, we have observed rotating pressure fluctuations in the experiment and valve-attached flow and local high-pressure region in the CFD result.These results show the pressure fluctuations in steam experiments and CFD is same kind of the fluctuations found in air experiment and CFD.

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